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Published on: September 16, 2025
Correlation Between Lens Density and Inter-Method Difference in Axial Length: Sum-of-Segments Versus Traditional
Mingzhen Yang1, Yujuan Zhang1, Danye Mei1
1Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong, Shantou, China.
Purpose:
To compare axial length (AL) measurements from a novel swept-source optical coherence tomography (SSOCT) biometer ZW-30 (sum-of-segments [SOS], traditional modes) (TowardPi Medical Technology Ltd) with the IOLMaster700 (Carl Zeiss Meditec AG), and evaluate the correlation between lens nuclear density and inter-device AL differences, as well as their impact on intraocular lens formula accuracy.
Methods:
Patients undergoing cataract surgery with preoperative biometry performed by the ZW-30 and IOLMaster700 were included. Lens density was quantified with SS-OCT scans using ImageJ software (National Institutes of Health). Correlations between lens density and AL differences were analyzed. Refractive prediction accuracy of the Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO), and the Prediction Enhanced by Artificial Intelligence and output Linearization-Debellemanière, Gatinel, and Saad (PEARL-DGS) formulas were evaluated 1 month postoperatively. Eyes were stratified into short (< 22.00 mm), medium (22.00 mm ≤ AL < 24.50 mm), and long (≥ 24.50 mm) AL groups.
Results:
In the entire cohort (n = 74), no significant AL difference was found among the three methods (P = .578). However, subgroup analysis revealed significant differences in medium and long eyes (both P < .01). Lens nuclear density correlated positively with AL in the entire cohort (r = 0.39 to 0.40, P < .001) and long AL group (r = 0.52 to 0.55, P < .05), and with AL discrepancy between ZW-30 SOS and IOLMaster 700 in long AL eyes (r = 0.49, P < .05). No correlation was found between lens density and formula prediction error (P > .05). The EVO and BUII formulas demonstrated significantly lower mean absolute error than the PEARL-DGS formula across all measurement modes (all P < .001).
Conclusions:
Agreement between the ZW-30 and IOLMaster700 appeared to decrease in medium and long eyes, with discrepancy correlating with lens density in long eyes, although this finding requires confirmation in larger samples. The EVO and BUII formulas provided favorable refractive predictions compared with the PEARL-DGS.
